Many existing garage doors have springs installed that function in extension to counterbalance the weight of the garage door. Such springs normally have integral retention hooks formed by bending of the spring material itself, and such springs often break at or near those hooks. While replacement springs are commercially available, they are relatively expensive compared to the cost of a repair kit that can make use of the remaining portion of a garage-door spring that has broken near one end. Thus there is a need for inexpensive and easy-to-install repair kits for extension garage-door springs. Since breakage &garage-door springs is so common as to justify marketing of replacement springs, another related need is a reinforcement for the end-attachments of conventional extension garage-door springs to prevent their breakage and thus to improve consumer safety.